﻿using System;
using System.IO;
using System.Web;
using System.Web.Hosting;
using System.Web.UI;

namespace Guan.CMS.Core
{
    public class PathHelper
    {
        private static string _applicationPath;

        /// <summary>
        /// 虚拟应用程序根路径
        /// </summary>
        public static string ApplicationPath
        {
            get
            {
                _applicationPath = HttpContext.Current.Request.ApplicationPath;
                if (!string.IsNullOrWhiteSpace(_applicationPath) && _applicationPath.Length == 1)
                {
                    _applicationPath = "";
                }
                return _applicationPath;
            }
        }

        private string _currentPath;

        /// <summary>
        /// 当前的绝对路径
        /// </summary>
        public string CurrentPath
        {
            get
            {
                _currentPath = HttpContext.Current.Server.MapPath(".").ToLower();//当前的绝对路径(这里MapPath里的"."代表当前服务器)

                if (_currentPath.Length == 1)
                {
                    _currentPath = "";
                }
                return _currentPath;
            }
        }

        /// <summary>
        /// 系统的根目录
        /// </summary>
        public static string RootPath
        {
            get
            {
                var rootPath = HttpContext.Current.Server.MapPath(HttpContext.Current.Request.ApplicationPath).ToLower();//当前的绝对路径
                if (rootPath.Length == 1)
                {
                    rootPath = "";
                }
                return rootPath;
            }
        }

        #region 将Web站点下的绝对路径转换为相对于指定页面的虚拟路径

        //第一个方法
        /// <summary>
        ///将Web站点下的绝对路径转换为相对于指定页面的虚拟路径
        /// </summary>
        /// <param name="page">当前页面指针，一般为this</param>
        /// <param name="specifiedPath">绝对路径</param>
        /// <returns>虚拟路径, 型如: http://www.cnblogs.com/ </returns>
        public static string ConvertSpecifiedPathToRelativePathForPage(Page page, string specifiedPath)
        {
            // 根目录虚拟路径
            string virtualPath = page.Request.ApplicationPath;

            // 根目录绝对路径
            string pathRooted = HostingEnvironment.MapPath(virtualPath);

            // 页面虚拟路径
            string pageVirtualPath = page.Request.Path;
            if (!Path.IsPathRooted(specifiedPath) || specifiedPath.IndexOf(pathRooted) == -1)
            {
                throw new Exception(string.Format("\"{0}\"是虚拟路径而不是绝对路径!", specifiedPath));
            }

            // 转换成相对路径
            //(测试发现，pathRooted 在 VS2005 自带的服务器跟在IIS下根目录或者虚拟目录运行似乎不一样,
            // 有此地方后面会加"\", 有些则不会, 为保险起见判断一下)
            if (pathRooted.Substring(pathRooted.Length - 1, 1) == "\\")
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "/");
            }
            else
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "");
            }

            string relativePath = specifiedPath.Replace("\\", "/");

            string[] pageNodes = pageVirtualPath.Split('/');

            // 减去最后一个页面和前面一个 "" 值
            int pageNodesCount = pageNodes.Length - 2;

            for (int i = 0; i < pageNodesCount; i++)
            {
                relativePath = "/.." + relativePath;
            }

            if (pageNodesCount > 0)
            {
                // 如果存在 ".." , 则把最前面的 "/" 去掉
                relativePath = relativePath.Substring(1, relativePath.Length - 1);
            }

            return relativePath;
        }

        //第二个方法

        //将Web站点下的绝对路径转换为虚拟路径
        /// <summary>
        /// 将Web站点下的绝对路径转换为虚拟路径
        /// 注：非Web站点下的则不转换
        /// </summary>
        /// <param name="page">当前页面指针，一般为this</param>
        /// <param name="specifiedPath">绝对路径</param>
        /// <returns>虚拟路径, 型如: ~/</returns>
        public static string ConvertSpecifiedPathToRelativePath(Page page, string specifiedPath)
        {
            string virtualPath = page.Request.ApplicationPath;

            string pathRooted = HostingEnvironment.MapPath(virtualPath);

            if (!Path.IsPathRooted(specifiedPath) || specifiedPath.IndexOf(pathRooted) == -1)
            {
                return specifiedPath;
            }
            if (pathRooted.Substring(pathRooted.Length - 1, 1) == "\\")
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "~/");
            }
            else
            {
                specifiedPath = specifiedPath.Replace(pathRooted, "~");
            }
            string relativePath = specifiedPath.Replace("\\", "/");
            return relativePath;
        }

        #endregion 将Web站点下的绝对路径转换为相对于指定页面的虚拟路径
    }
}